Method of flash butt welding



Oa. 22, 1935. M. .To 2,018,263

METHOD OF FLASH BUTT WELDlNG Original Filed May 17, 1.955

Patented` Oct. 22, 1935 UNITED sTATEs PATENT OFFICE METHOD OF FLASH BUTT WELDING original appucaaon my 17, 1933, semi No. 671,497. Divided and this application April 3, 1934, Serial No. 718,801. In Japan October 4,

2 Claims.

The present invention relates to a method of flash butt welding particularly to almethod of flash butt welding, which consists in pressing a metallic rod as an electrode, against a base metal sheet, while rotating it manually or automatically about its axis, this application being a division of `application Serial No. 671,497, filed May 17, 1933.r

The primary object of this invention is to provide an excellent flash butt welding method which drives out gas, slag, other foreign materials, etc., produced during the welding process to prevent the formation of blow holes at the welded part of a metal plate by the automatic rotation of the electrode about its axis.

This invention may be clearly understood from the detailed explanation of the accompanying drawing which shows this method and an apparatus for carrying it out into practice. However, let it be understood that the present invention is not limited to it, but various modifications may be made within the scope of the claims.

Fig. l shows a sectional front elevation of an automatic apparatus for carrying out into practice a method of flash butt welding of the present invention;

Fig. 2, a sectional view of the essential part of the apparatus as shown in Fig. l;

Fig. 3, a diagram of an electric connection for performing the flash butt welding according to this method, and

Figs. 4 to 8, several skeleton diagrams showing different steps of the flash butt welding operation.

Hitherto, as no attempt has been made to prevent the formation of blow holes at the welded part of a metal plate when a metallic rod is welded to it, their cohesive force is so weak that the welded rod is apt to be broken at its root by even the slightest mechanical shock in spite of its strong appearance.

'I'he method of the present invention removes such drawback. For convenienc'es sake, let me first explain the reason why the welded rod is brittle in the prior art.

Referring to Figs. 4 to 8, to weld a metallic rod I to a sheet metal 2 electrically, they are firstly brought into contact with each other as shown in Fig. 4 and electric current is passed to them to heat their contact surfaces. Then, the rod I is separated from the sheet 2 as shown in Fig. 5 to generate an electric-arc 3 and thereby to liquefy the part 4 of the plate 2 to be welded as shown in Fig. 6. Further, when the rod I'is presd-against the plate 2, the liquefied part 4 of the plate .swells around the rod I and this (Cl. 21S-10) swollen part 4" is cooled rapidly due to the extinction of the electric arc as well as the cool outside air. The metallic rod l such as a steel rod contains carbon, hydrogen, etc., so that when heated rapidly at a high temperature by the arc, these gases combine with oxygen in air and are converted into carbon mono-oxide, carbon dioxide or other gases-and expand suddenly on account of being hzated at a high temperature. Consequently, although the rod I appears to have been welded strongly as shown in Fig. 7, the occluded gas stays in the interior of the welded part and forms a blow hole as indicated by a dotted line 5. This is often broken at its root.

In the present invention, to remove the above drawback, when the rod I is pressed against the plate 2, it is rotated as if screwed into the plate as shown in Fig. 8 so as to destroy the shell of the blow hole 5 and thus to enable the occluded gas to escape outside and at the same time to smoothen the soft surfaces of the rod and plate by mechanically rubbing them against each other, so that even the occluded gas in the blow hole on the plate surface are driven out to entirely remove the blow hole from the welded part. Thus, a strong and satisfactory weld can be effected.

` Fig. 1 shows an example of an apparatus in which the method of this'invention is` put automatically into practice. In a casing 3 attached to the arm I of a handle 6 is enclosed an electromagnetic coil 9 a plunger I0 of which is adapted to be pressed down by a spiral spring Il in the normal condition, said plunger being lifted by the energization of the coil 9 supplied with electric current through lead wires and 3| from a suitable electric source. Into the upper part 32 of the casing 8 is screwed a cap 33 which is adapted to adjust the elastic force of the spring Il and which comprises an abutting rod 34 surrounded by a small spiral spring 35, said rod serving to absorb the inertia of the mechanical shock of the lifting plunger I0. Integrally with the frame I2 secured to the case 8 at its lower end by means of screw threads, a suitable pair of guide members I3 extends along the inside surface of the case 8 and engages with the grooves I5 cut at the base I4 of the plunger I0.

To the lower surface of the base plate I4 of the plunger Ill there is secured by means of screws 36 a member IB which comprises a tubular member I'I having an annular rim I8 on its inner surface. Three members I9, 20 and 31 are tightly secured as one block to a rod 22 by means of a screw 2I, and the combination of these members is mounted rotatably upon the annular rim Il in such a `manner that the rod 22 rotates freely. The rod has cut thereon a screw thread 24 adapted to engage with the teeth of a guide plate 23 which is fixed to the lower end of the frame I2 by means of screws 39. The rod 22 with the screw thread 24 is provided at its to'p end with a knurled disk 40 connected through a lead wire 4I to a suitable electric source. With the disk 40 at its lower threaded part is engaged a cap 42 adapted to hold tightly an electrode in a grasping means 25 by turning said cap.

The following is the briei' explanatlonnof the operation of this invention with reference to the schematic diagram ofthe electrical connection as shown in Fig. 3:-

As the spring l I presses the plunger. I0 towards the metal plate 2 to push the electrode I against it in the normal condition, the current is passed through the electrode and plate from the suitable electric source 21 when a switch 26 is closed. Next, a switch 28 is closed to excite the coil 9, and

Y the plunger I0 will be raised straightly without tric arc 3 and melt the electrode and the part or the plate to be welded. On this occasion. if the switch 28 is open, the coil 9 will be deenergized and the spring I I will press the plunger I0 against the plate 2 while the electrode is turning in the direction indicated by an arrow 29 as shown in 5 Fig. 4, thus bringing it into contact with the suri'ace of the plate and driving out the occluded gas from the melted'part, so that the contact surface of the plate is made smooth and the rod may be welded to the plate tightly. 10

I claim: f

1. A method of flash butt welding, which consists in bringing a metallic rod into contact with a metal sheet, passing an electric current through the contact portions of thel rod and sheet, sepa- 15 rating said rod .from the sheet to generate an electric arc until thev contact portions have reached a welding temperature and rotating the metallic rod about its axis while it is forcibly pressed against the sheet metal. 2 2. A method of flash butt welding, which consists in bringing a metallic rod into contact with a metal sheet by an elastic means, passing an electric current through the contact portions of the rod and sheet, generating an electric arc beg5 tween said rod and sheet until the contact portions of the rod and sheet have reached a welding temperature and rotating the metallic rod about its axis while it is forcibly pressed against the sheet metal.

MASAJI ITO. 

